I don't know what Z travel is but if you're referring to pass travel sometimes nonrev travel is just impossible for families. I don't work for either UAL or UPS but from what I understand from friends who work at both FDX and UPS they both do a lot of company business travel on the pax airlines. That occurs enough that most all enjoy high status along with upgrades often when they fly along with reward miles. When it is time to go on vacation they can redeem free travel with the miles they have accumulated. It can be nice having positive space travel and not stressing over whether you're going to get on a flight or not. I am retired from a pax airline and personally would prefer fly pax, but if I was just concerned with traveling I don't think the benefits from working for UPS or FDX can be beat.